In closures of this kind, the application of the tightening force is performed by means of a tension lever pivoted on one end of the tension ring, and by means of a connecting link pivoted on the other end of the tension ring and on the tension lever. To secure the closure, the ring end that is joined directly to the tension lever has a shackle to accommodate a safety lock. The safety lock is threaded through lateral eyes in the tension lever when the tension lever is in the folded-down, locking position.
The securing of the tension lever to assure the originality of the packaging as described above provides a degree of strengthening of the closure under severe handling conditions. However, this strengthening is not considered sufficient, especially when a filled container is dropped. The tension ring ends overlap and one is clamped by a securing means, but the other ring end remains unsecured and is able to slip out and open up when the container is dropped. Thus, the means for security against unintentional opening, the shackle and safety lock, act virtually like a pivot around which the free ring end unwinds. The closure is thus destroyed.